Spring is in the air and there are plenty of ways to celebrate it this weekend.

*You can go daffy at the Washington Daffodil Society Show where there'll be hundreds of varieties of daffodils, arrangement competitions, educational exhibits and a chance to order bulbs for your own garden. The free show is at the U.S. Botanic Garden Conservatory on Maryland Avenue and First Street SW near Capitol Hill and runs Saturday from 2 to 5, Sunday 9 to 5. 225-8333.

*Stroll in some of the finest gardens in town on the 58th Annual Georgetown Garden Tour Saturday from 10:30 to 5. This is the time each year when some of Georgetown's best green thumbs open up their backyards for public inspection. In addition to all the trees, flowers and shrubs, you can see sculptures, fountains and a Marc Chagall mosaic mural. The self-guided walking tour is of 10 private gardens within a 10-block area of Georgetown plus Dumbarton Oaks, where you can get your tickets and a map of the gardens on the tour. Dumbarton Oaks is at R and 31st streets NW. Tickets are $10 and include a tea from 2 to 5 at the Georgetown Children's House on N Street between Wisconsin Avenue and Potomac Street NW. All proceeds benefit the day care center. 333-4953.

*Historic Garden Week in Virginia kicks off Sunday from 1 to 4 with an open house at Green Spring Farm Park, where you can tour the horticulture center and greenhouse and see an exhibition of garden art on loan from the Museum of Fine Arts in Richmond. You can also stroll the 27 acres of gardens and woods of the farm, which is at 4603 Green Spring Farm Park in Annandale. Other garden events run through the week at Green Spring Farm and other Virginia parks. For more information, call the Fairfax County Park Authority at 941-5000 or at the park at 642-5173.